Leashable API

paper-api/src/main/java/io/papermc/paper/entity/Leashable.java

@@ -0,0 +1,37 @@
+package io.papermc.paper.entity;
+
+import org.bukkit.entity.Entity;
+import org.jspecify.annotations.NullMarked;
+import org.jspecify.annotations.Nullable;
+
+/**
+ * Represents an entity that can be leashed.
+ */
+@NullMarked
+public interface Leashable extends Entity {
+
+    /**
+     * Returns whether the entity is currently leashed.
+     *
+     * @return whether the entity is leashed
+     */
+    boolean isLeashed();
+
+    /**
+     * Gets the entity that is currently leading this entity.
+     *
+     * @return the entity holding the leash
+     * @throws IllegalStateException if not currently leashed
+     */
+    Entity getLeashHolder() throws IllegalStateException;
+
+    /**
+     * Sets the leash on this entity to be held by the supplied entity.
+     * <p>
+     * This method has no effect on players.
+     *
+     * @param holder the entity to leash this entity to, or {@code null} to unleash
+     * @return whether the operation was successful
+     */
+    boolean setLeashHolder(@Nullable Entity holder);
+}

paper-api/src/main/java/org/bukkit/entity/Boat.java

@@ -7,7 +7,7 @@ import org.jetbrains.annotations.NotNull;
 /**
  * Represents a boat entity.
  */
-public interface Boat extends Vehicle {
+public interface Boat extends Vehicle, io.papermc.paper.entity.Leashable { // Paper - Leashable API
 
     /**
      * Gets the wood type of the boat.

paper-api/src/main/java/org/bukkit/entity/Mob.java

@@ -8,7 +8,7 @@ import org.jetbrains.annotations.Nullable;
 /**
  * Represents a Mob. Mobs are living entities with simple AI.
  */
-public interface Mob extends LivingEntity, Lootable {
+public interface Mob extends LivingEntity, Lootable, io.papermc.paper.entity.Leashable { // Paper - Leashable API
 
     // Paper start
     @Override